Wheelchair seat cushions are designed to perform a number of important functions. A seat cushion should be comfortable and capable of providing proper support for optimal posture and posture control, for a considerable length of time. A seat cushion should create stability and security for the person within the wheelchair. Seat cushions are often designed to help prevent and reduce the incidence of local pressure created by prolonged sitting on the cushion trying to uniformly spread the pressure on the external surface of the seating organs of the individual.
Many prior art attempts have been made to generally or individually fit the shape of the seat cushion to the anatomical shape of the user. For example, U.S. Pat. No. 4,588,229, given to Eric Jay, provides a seat cushion for the human body which comprises a pad comprising a flexible envelope containing a fluid filling material.
U.S. Pat. No. 4,819,286, given to David Beauchamp, provides a dry flotation cushion used on wheelchairs and a method for supporting dry flotation cushion used in wheelchairs. The structure includes a substantially rectangular rigid plate for inserting into the fabric covering of a dry flotation cushion for improving the support provided by a plurality of dry flotation cells when the dry flotation cushion is supported on the side frame members of a wheelchair.
U.S. Pat. No. 7,220,376, given to Thomas Hetzel et al, provides a negative impression of an anatomical portion of a person is captured by forcing the anatomical portion into impression foam to collapse the impression foam into the negative impression. The negative impression is obtained by collapsing the impression foam within the range of constant-force collapse distances, thereby creating the negative impression under conditions which reflect an equally-loaded anatomical portion. This invention is then used to fabricate wheelchair seat cushions.
U.S. Pat. No. 6,009,578, given to Steve Davis, provides a seat cushion for a wheelchair including a resilient wedge-shaped pad having an upper surface at an incline sloping downwardly from a higher end to a lower end. A plurality of spaced apart gel packs are on the upper surface of the resilient wedge-shaped pad. The gel packs closest to the higher end are of a high density, while other gel packs will decrease in density toward the lower end of the resilient wedge-shaped pad. The seat helps preventing a person from sliding off of the wheelchair.
The prior art shaped seat cushion are typically expensive to manufacture and do not necessarily address the problem encountered by handicapped individual, such as elderly individuals, that are sliding forwardly on top of the seat and are not able to pull themselves back. Often, a handicapped individual is not even aware of being in a slid seating position.
Reference is made to FIG. 2 (prior art), which is a cross-sectioned view showing person 10 properly positioned in wheelchair 20 seating system, on seat cushion 50. The back of person 10 is supported by back 30 of wheelchair 20. Pelvis 15 supported by both the lower end of back 30 and the end of seat cushion 50 proximal to back 30.
Reference is also made to FIG. 3 (prior art), which is a cross-sectioned view showing person 10 who has slid forward (in direction 40) and thereby improperly positioned in wheelchair 20 seating system, on seat cushion 50. Pelvis 15 is positioned away from the lower end of back 30 and is and is pointy pressing against seat cushion 50, thereby causing person 10 to develop decubitus ulcers. Furthermore, the sliding motion cause rubbing of the external surface of pelvis 15 of individual 10. Furthermore, as person 10 slides on seat cushion 50, the sliding motion accelerate as vector FH, derived from the weight vector FV of person 10, is added to the motion forward in direction 40.
Reference is also made to FIG. 4 (prior art), which is a cross-sectioned view showing person 10 who is seating on wedge seat cushion 52, which is designed to prevent a seated handicapped individual 10 from sliding forward on seat cushion 52. Pelvis 15 is positioned away from the lower end of back 30 and is pointy pressing against seat cushion 52, thereby causing person 10 to develop decubitus ulcers.
There is a need for and it would be advantageous to have a seat cushion that prevents a seated handicapped individual from sliding forward on the seat, while preventing the occurrence of decubitus ulcers. It would be further advantageous for the seat cushion to be simple and inexpensive to manufacture.